I wrote this piece below to brief some US colleagues, but thought it might be worth sharing with a broader audience for what’ it’s worth.
The coding of drugs and medical devices in the UK is based on the NHS’s Dictionary of Medicines and Devices (dm+d) which is very closely related relevant sections of SNOMED (all dm+d identifiers are SNOMED codes).
It provides a hierarchical representation of medicines starting from Virtual Therapeutic Moieties down to individual manufactures packs as illustrated in this diagram taken from the the dm+d website
dm+d also contains a “Trade Family” Class which is equivalent to the VTM class to allow the prescription of those small number of branded medicine where no VTM exists (eg Lipitor) which could otherwise only be prescribed at the AMP or AMPP level which is at odds with usual inpatient prescribing practice which occurs at VTM level. Trade Family TF and the associated Trade Family Group (TFG) and more fully described in the SNOMED CT® UK Drug Extension Editorial Policy .
Despite it’s name medical devices coverage in dm+d is very limited with coverage by and large only extending to medical devices listed in the NHS Drug Tariff which includes all items including medicines, dressings, appliances, reagents and devices that can be prescribed on the NHS by UK general practitioners.
VTM, VMP,TF and TFG concepts exists as part of the core SNOMED namespace while VMPP and AMPP concepts form part of the UK extensions to SNOMED
The dm+d contains includes medicines by both generic name (usually aligned to International Nonproprietary Names ) and UK trade names and is designed to promote generic prescribing (the usual UK practice) for all medicines except in those few cases where generic prescribing is clinically contraindicated (even when only branded products are available to fill such prescriptions).
dm+d contains information about drug forms, strength, and licenced routes of administrations, but contains little other clinical information about the drug. However, it does provide mechanisms to link dm+d to a range of drug knowledge sources (e.g. the British National Formulary BNF) and many commercial drug knowledge suppliers maintain mappings from dm+d to their proprietary identifiers of have adopted dm+d as their native coding. These links allow prescribing based on dm+d to be link to a range of knowledge sources and prescribing decision support tools.
dm+d also contains a large number of data and metadata items related to UK pricing, regulatory, best practice and supply chain operation (including links to the information in the Drug Tariff) which will be required by ePrescribing systems that wish to comply with UK statutory, regulatory and best practice recommendations and operate satisfactorily with medicines supply chain arrangements that apply in the NHS. There is a considerable volume of useful guidance on the implementation of dm+d freely available via the web with the dm+d web site providing a good start point from which to find this.
There are a numbers of sources of high quality UK specific drug information and knowledge to support both professional responsible for prescribing and administering medicines and patients which can be incorporated in to prescribing and medicines management systems. Information in these sources includes both eye-readable information (manufacturer’s data sheet (SPC’s), drug monographs, warnings, prescribing guidelines, patient information leaflets etc) available to the relevant actor at appropriate points in the treatment process and machine readable data and metadata intended to support automated prescribing, dispensing, administration and associated decision support. Such data will be provide in a structured and coded format to facilitate automated processing and may be supplied with computable decision support rules and/or software components and APIs to aid it’s implementation.
Computable data is typically intended to support functions that might include.
- Therapeutic recommendations
- Drug-drug interactions
- Drug-lab interactions
- Drug contraindications
- Dose recommendations/calculations
- Dose range checking
- Defined daily doses
- Cross-sensitivity allergy checking
- Drug administration
- Side-effect identification
- Drug substitutions
- Drug-Gene interactions
Drug knowledge suppliers assemble their data from a range of primary and secondary sources. Each provides a different range of data which is likely to be provided in a proprietary format using a variety of open and proprietary coding systems. Common coding systems found in UK data sources include (Read, CTV3, (widely used in UK general practice), dm+d, ICD, SNOMED (Op sit), ATC, BNF, PIP) mappings exist (of variable completeness and quality) between many of these systems where their domains overlap – Coding systems common in the US like NDC and LOINC are rarely found in UK drug knowledge sources (although some direct and indirect mappings may exist).
There are some significant differences in regulation and prescribing practice, reflected in the way medicines are supplied, between Europe and the USA, which affect (while there are also differences between individual European countries there is increasing harmonisation across the EU and EEA) drug information requirements and ePrescribing and medicines management and administration systems.
- Drug names both generic and trade names can be different for the same drug
- The range of forms/strengths available can be different
- Licensed indications can be different and some drugs available in the US may not be available at all in the EU and vice versa
- Legal classification are different and often not directly comparable
- Most medicines in the EU are supplied and dispensed in patients packs (invariably blister packs for solid medications) – For drugs with a short duration of use these pack will be designed to provide one course of the medicine, for drugs with a longer or indeterminate period of use patients pack will generally be for 28 days supply, although other sizes of patient pack exist for some drugs. Bulk packs of medicines designed to be dispensed into vials, compliance and unit dose systems and medicines pre-packed for unit-dose dispensing are NOT generally available. This reflects the very low levels of unit-dose dispensing in UK hospitals compared to the US which is probably the single most significant difference in medicines management practice between US and UK hospitals.
References to further information about issues covered are generally included as hyperlinks in the text above. Additional sources of note:
British National Formulary BNF – The UK “Gold Standard” for medicines information and guidance on prescribing.
Royal College of Physicians – Standards for medication and medical device records – technical annex Contains and points to some of the latest work
NHS – dm+d Implementation Guide (Secondary Care) 2009, but still full of relevant, useful and detailed information